Like I said in my original message - every manufacturer is different when it comes to VRLA batteries.
The problems we have seen with gel batteries is not at room temperature, but at the elevated temperatures like you often see in hot climates, like in Arizona. However, I cannot find any actual specifications on temp vs charging rate on the Deka/MK batteries. .................................................................................................. Northern Arizona Wind & Sun - Electricity From The Sun Since 1979 Solar Discussion Forum: http://www.wind-sun.com/ForumVB/ .................................................................................................. ----- Original Message ----- From: Walt Ratterman To: 'Larry Crutcher, Starlight Solar' ; 'RE-wrenches' Sent: Tuesday, June 30, 2009 3:19 PM Subject: Re: [RE-wrenches] Solar Boost Controller in Senegal Hello Larry and others.. The slow charge rate for the Gel's you mention confuses me further. I had just finished researching this last week when I was in Sierra Leone, where we were setting up the DEKA 225AH Gel batteries on an Outback system, and checking the charge rate. I downloaded a charging instruction document from DEKA and was quite surprised. On the bulk charge rate, Rolls recommended 15% of C6. HUP recommends a minimum of 10% to a maximum of 20% of C6. But..DEKA recommended, for their GELS, "Maintain <= 30A per 100AH of C20 Rating. That's twice as fast as the Rolls!! Maybe I am reading this incorrectly. And, in the DEKA's advantages / disadvantages sheet, they list quicker charging as one of the GEL's advantages. I can forward any of you this DEKA charging sheet if you want, but I don't think it is OK through the list serve. Thanks, Walt From: Larry Crutcher, Starlight Solar [mailto:[email protected]] Sent: Tuesday, June 30, 2009 1:37 PM To: [email protected]; RE-wrenches Subject: Re: [RE-wrenches] Solar Boost Controller in Senegal Hi Walt, You are right! Gel batteries will give many more cycles than AGM's. And they cost more so you you are not getting an equivalent value by them suppling AGM's. A very big downside to Gel is if you accidently over-voltage the battery, you can permanently ruin it. I have seen many battery banks damaged from accidental high voltage charging. For that reason, I mostly sell AGM (in my market). They also charge slower because of the reduced charge voltage required. Also they are not quite as efficient as AGM so it takes more power/time to fully recharge. On the plus side, an AGM battery can be equalized if needed but never a Gel battery. Hope this helps. Kindest Regards, Larry Crutcher Starlight Solar (928) 941-1660 Renewable Energy Products, Service and Installation Mailing Address (NO SHIPPING): 11881 S Fortuna Rd. #210 Yuma, AZ 85367 Shipping and retail store (NO MAIL): 2998 Shari Ave Yuma, AZ 85365 On Jun 30, 2009, at 2:43 PM, Walt Ratterman wrote: Hello, Why do you say that AGM batteries are a better choice? I have been reading about the differences, and all I see (comparing DEKA Gel versus DEKA AGM is that the cycle life of the AGM (at 50% DOD) is 500 cycles versus 1000 cycles for the Gel. The AGM seems to have better resistance to freezing, but of course that is not a concern here. What are the benefits of AGM that I am missing here? (This could be important, because I was going to jump all over the fabricator for shipping AGM when the literature quotes GEL, and I was thinking GEL would have been a better choice. Maybe they were trying to right think, but I would need to be educated more here. Thanks!! Walt From: Wind-sun.com [mailto:[email protected]] Sent: Tuesday, June 30, 2009 7:30 AM To: [email protected]; RE-wrenches Subject: Re: [RE-wrenches] Solar Boost Controller in Senegal The AGM batteries are probably a better choice than gelled, but the fact that some are down to 5 volts is the real problem. A typical AGM will lose around 1-2% charge per month at 25 degrees C. If they are at 5 volts, that indicates that they either sat around for over a year unused and uncharged, and possibly in a very high temperature environment. The 2nd possibility is that there is some kind of constant load on them, even when the units are not turned on - which would be poor design. The Midnite controller is not available yet, so your only real choices with the panels you have are the Outback FM60 or the Xantrex XW-SCC - both of them are in the $600 range. .................................................................................................. Northern Arizona Wind & Sun - Electricity From The Sun Since 1979 Solar Discussion Forum: http://www.wind-sun.com/ForumVB/ .................................................................................................. __________ Information from ESET NOD32 Antivirus, version of virus signature database 4193 (20090626) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ------------------------------------------------------------------------------ _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
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